The widespread use of poured concrete in buildings, especially commercial buildings, has a number of virtues, including a great reduction in fire risk, speed and ease of production, and low noise transmission between floors. In concert with the growth in the erection of concrete buildings, a variety of devices have been developed to assist in the attachment of fittings and equipment, particularly, electrical and plumbing fittings, to such buildings. Although it is relatively easy to drill a hole in concrete and to insert an anchor therein, it is a relatively time consuming procedure compared with simply driving a nail or a staple in wood.
This problem has led several manufacturers to develop and sell products to the construction industry known generally as powder actuated tools, explosive actuated tools, bolt setting guns, power hammers, RAMSET (trade mark) guns or Hilti (trade mark) guns. The concept common to all these devices is the use of an explosive or propellant charge, which is detonated inside a hand-held gun, to propel a metal object such as a threaded bolt into a hard surface, typically a concrete wall. These guns are used extensively by electricians and plumbers so that plumbing pipes and electrical cables may be hung on the fastening devices fixed in the concrete.
Disposable magazines for use in explosive powder driven bolt setting guns have been known and certain disadvantages have been experienced with types of propellants formed with non-ferrous metal casings as well as with caseless propellant charges.
Manufacturers currently manufacture the cartridges or containers for the explosive charges by deep-drawing brass into a shape resembling a small calibre bullet except that there is no slug at the top of the bullet. At least one manufacturer inserts the cartridges into a plastic strip so that the gun can be used in a semi-automatic fashion rather than a single shot mode. Typically these devices include drive engaging means (eg. notches) formed on the strip so that the strip can be advanced by the gun and properly aligned with the firing hammer or detonating pin in the gun to thereby explode the respective charge.
A serious problem with the constructions disclosed in the prior art is high expense. Typically the magazine component that contains the propellant is a two component system comprising a plastic carrier, having a series of holes, and brass cartridges that fit into the holes. Brass is expensive, and the deep-drawing of brass is a complex expensive art.
The primary disadvantage experienced with cartridge shells formed from non-ferrous metal such as brass is raw materials expense and manufacturing expense to form the cartridge shell. The metal must be annealed several times before cartridge forming is completed. Because of such cost, several variations of caseless propellants have been known, which for reasons of expense and safety were intended to completely eliminate the use of non-ferrous metals.
A further disadvantage with cartridge shells formed from non-ferrous metal occurs where hot burning gases from ignition unintentionally leak into the firing mechanism of the tool. Yet a further disadvantage of cartridge shells formed from non-ferrous metals is that regardless of the powder load used, the interior volume of the shell is not variable. A common method of reducing the firing impact for light loads is to dilute the powder with paper or other fillers. This creates an undesirable result because it increases the amount of residue and impurities that can penetrate into the firing mechanism of the tool.
Caseless charges have been designed in order to avoid the expense of deep drawing non-ferrous metals. Disadvantages have been experienced with such caseless charges however, because dangerous ignition of adjacent propellant charges has sometimes occurred due to lack of a combustion sealing mechanism between the cartridges. A caseless charge magazine which eliminates this danger is disclosed in U.S. Pat. No. 4,406,079 which describes a strip of caseless charges wherein the propellant charge is displaced into the gun for ignition. Because of this requirement, the system is incompatable with one of the more widely used types of guns because substantial differences occur in the type of powder actuated gun in which the propellant can be used.
The following references disclose subject matter which is pertinent to the technology of gun powder or explosive actuated tools and explosive firing devices (guns).
U.S. Pat. No. 2,918,868, Ringdal, issued December 29, 1959 discloses an invention relating to a cartridge comprising a base having a tubular extension and a case which consists of relatively elastic flexible synthetic resin material, such as polyethylene or polyvinylchloride. The attachment of the case and cartridge base to each other is secured by means of a bead on the one member in engagement with a corresponding groove in the other member.
U.S. Pat. No. 3,318,245, Ferri et al., issued May 9, 1967 discloses strip ammunition for toy guns wherein a plurality of discrete explosive charges are contained in container means. Stalk means interconnects each container means, Stop means are formed on the stalk means for engagement by an advancing means of a toy gun. In this way the strip can be advanced by the space between each container means each time the gun is fired.
U.S. Pat. No. 4,294,173, Ferri, issued October 13, 1981, discloses ammunition for a toy-weapon comprising an injection molded support having seats for explosive charges. The charges are sealed within the seats by a separate cover for each seat. The covers are injection moulded simultaneously into the seats of the support.
U.S. Pat. No. 3,349,710, Sposimo, issued October 31, 1967 discloses a strip carrier for explosive socket caps for toy guns. The explosive is encased in wells which are capped by a series of caps strung together in series.
U.S. Pat. No. 3,583,087, Huebner, issued June, 1971 discloses a certain design of magazine.
U.S. Pat. No. 3,611,870, Udert, issued October, 1971, discloses a cartridge magazine construction in which the cartridge is placed in a narrow band having a plurality of tubular projections formed therein. Each projection holds a single cartridge.
Gawlick et al. have been active in this area. U.S. Pat. No. 3,625,153, issued December, 1971, discloses a plurality of plastic propellant cases formed in series on a base.
U.S. Pat. No. 4,036,103, Gawlick et al., issued July 19, 1977, disclose a magazine apparatus for accommodating propellant charges including a flat coilable metal strip having a plurality of holes extending transversely therethrough for accommodating the insertion of cartridges. Cartridge holding collars are formed at each of the holes by bulging or plastically deforming the strip in the region of these holes so as to form a clamping seal spaced from the plane of the strip for clampingly engaging cartridges held at the strip. Various preferred embodiments include various cross-sectional configurations of the holding collars. The method of making the magazine apparatus includes forming the collars by a multiple-step bulging process wherein the last bulging step is formed by the cartridges as they are inserted into position on the strip.
U.S. Pat. No. 4,098,169, Gawlick et al., issued July 4, 1978, discloses an ammunition belt apparatus for accommodating propellant cartridges including a flexible, coilable belt strip, a plurality of holes extending transversely through the strip and spaced from one another in the longitudinal direction of the strip. Clamping means are associated with each of the holes for clamping a cartridge to the strip with portions of the cartridge extending through one of the holes. Parts of the clamping means are formed separately from the strip and the cartridge. In preferred embodiments, the clamping means includes a tubular casing formed separately from the strip for each of the holes. The tubular casing press-fittingly engages a respective cartridge for holding the cartridge in position on the strip with the casing. A cartridge rim clamps the strip therebetween.
U.S. Pat. No. 4,056,063, Walser et al., issued November 1, 1977, discloses a magazine for use in an explosive powder driven bolt setting gun. A cartridge holding space for a caseless charge is formed by the combination of a cartridge recess in a band-shaped magazine body and a torus-shaped body superimposed on the magazine body to form an extension of the recess. Various configurations of the cartridge holding space and the exterior of the torus-shaped body can be used. A variety of openings can be provided through the cartridge holding space to prevent destruction of the magazine parts when the caseless charge is ignited.
U.S. Pat. No. 4,406,079, Buechel, issued September 27, 1983, discloses a magazine for caseless propellant charges, such as those used in a fastening element setting device. The magazine consists of an elongated strip-like member. Cut-outs are provided in the strip-like member and a caseless charge holder is secured in each cut-out by webs. A caseless charge and the holder are displaced out of a cut-out when a sufficient force is directed against the holder to separate the webs from the strip-like member.
U.S. Pat. No. 4,565,114, Burdick et al., issued January 21, 1986, discloses a cartridge magazine for holding cartridges for feeding to the barrel of an explosion driven fastener setting tool. The magazine comprises an elongated flat flexible strip or band preferably made of an inexpensive material such as plastic. The strip includes a plurality of stepped projections defining cartridge holding recesses arranged at equally spaced locations along the strip and lateral recesses for advancement. Each cartridge holding recess is defined by a stepped projection extending upwardly from the strip which on its exterior is stepped inwardly in a direction toward the tip of the cartridge. The angular taper of each of the outside walls of this portion on the cartridge magazine is slightly less than one cone angle of the cartridge chamber of a gun barrel with which it is to be employed. In this way there is more than one sealing point between the projections and the inner wall of the cartridge chamber.